[ Beatrice Farmer wrote in 140301 MMDigest:

> The engine plays a tune with whistles that are engaged when a bump
> on the track is run over.

My kids had something similar back in the late 1960s or early '70s,
from Tomy or some toy maker like that, except that the tune was
supplied by different-colour (and pitch) "railroad ties" that slipped
in between the rails and hit by a reciprocating "hammer" in the bottom
of the locomotive.  So this is hardly a "new" idea -- it's sort of like
having a piano play itself... ";-)

Bob Loesch
Northern California, USA